Is there a difference between child molestation and child sexual abuse?

Possibly: These are words. You could try to define them very precisely. But, the bottom line is, in my opinion, that it doesn't matter. Both words mean that bad things were done to a child.

Semantics: Each of these diagnoses and terms could mean a host of things. They might overlap and they might not depending upon what one means when they use the term. In essence, they mean the same thing however - abuse of a child involving inappropriate sexual contact. Semantics or splitting hairs.